The present invention relates generally to pneumatic tires, and more particularly to the tread portion of a pneumatic tire wherein said tread portion is asymmetric with respect to the mid-circumferential plane of the tire.
It is generally recognized in the tire art that a tire with a directional tread design has lower noise generation characteristics, when rotated in the direction that it is designed to rotate in, than a tire having a non-directional tread design. As used herein a "directional tread design" is a tread structure that is intended to operate more efficiently when rotated in one direction than in the opposite direction, and a "non-directional tread design" is a tread structure that is intended to operate with equal efficiency regardless of the direction in which it is rotated.
The present invention provides a tire having an asymmetric tread structure with lateral edge portions that are directional and a central portion that is non-directional.
A pneumatic tire having a tread according to the preferred and most preferred embodiments of the present invention may be referred to as an all season tire. An "all season tire" is a tire with a tread portion adapted to provide good wet and snow traction while still maintaining good dry traction, tread wear, noise levels and handling. It is understood that in order to provide these desirable characteristics for an all season tire it is necessary to compromise the levels of some characteristics because, for example, a tread portion that provides a very good level of wet traction or snow traction performance generally has poorer dry traction, handling and/or noise levels.
A pneumatic tire having a tread portion according to either the preferred or most preferred embodiment of the present invention is suitable for use in all seasons of the year and provides good wet and snow traction while still maintaining good dry traction, tread wear, noise levels, and handling.